There is growing concern in international circles over the development of the Iranian nuclear reactor at Arak.

According to Reuters, the US is “deeply troubled” by Iran’s plans.

US Ambassador to the International Atomic Energy Agency, Joseph Macmanus, said: “We are deeply troubled that Iran claims that the IR-40 heavy water reactor at Arak could be commissioned as soon as early 2014, but still refuses to provide the requisite design information for the reactor."

The West is concerned that Iran is using the cover of a civilian atomic energy project to take further steps towards the development of a nuclear weapon.

An EU representative said Iran's expansion of its nuclear activities, including its Arak plans, and lack of transparency towards the IAEA, "further aggravate the international community's existing concerns".

Alistair Burt, a UK Foreign Office minister, tweeted his "concern" over Iran's plan to "install more centrifuges, adding to stockpile & continued activity at Arak.”

The increasing lack of transparency Iran has shown with regards to its nuclear programme confirms Israeli fears that international sanctions are ineffective in halting its acquisition of nuclear weapons.

Israel’s strikes on reactor sites in Iraq and in Syria in 2007 revealed its determination not to allow regional foes to acquire the means to assemble nuclear weapons.

A month ago, former Israeli intelligence official, Amos Yadlin said, speaking about Iran, that “we are heading toward a collision course by the end of next year”. He went on to say “we have two months to sleep safely”.

In a rare showing of international unity, powers that were previously reluctant to condemn Iran such as Russia and China have solidified their backing for international sanctions against the regime.

This week they joined Western powers in pressing Iran to co-operate with a stalled UN investigation into its nuclear programme.

According to Reuters, in a joint statement, the six powers said they were "deeply concerned".